Openhab interconnection

I would like to exchange some data with openhab using mqtt

How can I either:
publish some data to a second mqtt server
or instruct openhab to import some data from emoncms?

I set up a second broker that corresponds to the mqtt server on emoncms. I want to read the power consumption values

I created a thing that reads the mqtt topic from emoncms
I created some items corresponding to emoncms thing

So data is being imported into openhab